Adhesive medical and surgical dressings



June 14, 1960 A. e. PATCHELL 2,940,868

ADHESIVE MEDICAL AND SURGICAL DRESSINGS Filed May 16, 1956 WET ADHESIVE MASS 2 Sheets-Sheet l MAIN ROLLER I STIF FE ADHESI STIFFENING ADHESIVE ADHESIVE ST FFENING 3/ AD HESIVE June 14, 1960, A. e. PATCHELL ADHESIVE MEDICAL AND SURGICAL DRESSING-S Filed May 16, 1956 2 Sheets-Sheet 2 Edi/7 MEDICATED PAD MEDICATED PAD Patented June 14, 1950 2,940,868 ADHESIVE MEDICAL AND SURGICAL DRESSINGS Albert George Patchell, Welwyn Garden City, England, assignor to T. J. Smith & Nephew Limited, Yorkshire, England, a British company 7 Filed May 16, 1956, Ser. No. 535,257 Claims priority, application Great Britain'May 26, 1955 5 Claims. Cl. 117-38) adhere to the applied surface of the porous backing and effect, by the continued turning of the main and transfer ro1lers,-the'r'ead'y transfer of the patterned adhesive mass to the porous backingwithout excessive stringing, as the stiffer readily adhesive and more cohesive mass readily separates from the" wet adhesive mass of lower cohesion located at and towards the base of the grooves, to leave a certain amount of this wet adhesive mass of lower-co hesion atthe base of the grooves, which then return through a minimum-angular-distance'to the supply zone 7 for re-filling and repetition of the cycle.

This invention relates to adhesive medical and surgir cal dressings of the type comprising a backing which is porous, which latterterm 'must be regarded here n as extending from the highly porous to themicro-porous,

coated on one side with a patterned spread of pressuresensitive rubber based adhesive sufficient upon-application to give adequate adhesion to the skin but leaving a multiplicity of small uncoated areas :for the escape of perspiration to constitutea wholly porous dressing.

Attempts have been made to transfer a pattern of sol- Wha'tever the-exact dimensions of the parts andtheir arrangement, the speed of operation-can be adjusted so' that by the time the surface of the main roller having the filled grooves. comes into contact with the porous backing to belspread, the greater part of the adhesive mass in the grooves has been conditioned toacquire the necessary cohesivenessand surface adhesive strength, to leave the remaining partof the mass at the base of the grooves still in a wet state. The more cohesive portion of the mass adheres to the porous backing with which it is brought into-contact andreadily separates itself .away

vent-thinned pressure sensitiverubber based adhesive di-f rectly to a backing by a. process utilising'a grooved roller as a feeding carrier for the adhesive and to some extent resembling .intaglio. printing, but these have failed owing to the characteristics of the pressure-sensitive adhesive masses.

When the mass is -wet, that is when it contains a;'

relatively high proportion of J solvent, the amount'o'f ad-.

hesive transferred from the feeding carrier to the backing is small and insufiicierit to 'give adequate adhesion to the skin. If, however,; a stifier, more cohesive adhesive mass containing a relatively low proportion of solvent is used, the patterned adhesive mass tends to remain adherent to the feeding carrier and excessive stretching or stringing of said mass occurs at the transfer position between the carrier and the backing, which is ofsuch extent that hitherto the desired result has not been attained.

According to the present invention, a method of applying a patterned spread of solvent-thinned pressure sensitive rubber based adhesive to the porous backing comprises utilising as a carrier for thepatterned adhesive mass, a slowly turning main roller of metal or other suitable material, for example a plastic material such as polythene, the cylindrical curved surface of which has' cut thereon shallow grooves which'may cross as desired, the uncut portions of the surface being a defined proportion of the total surface and the uncut and. grooved portions being distributed 'in a uniform manner over the curved surface, to which grooves, while the roller is turning, the adhesive mass in a relatively wet state, is supplied at one circumferential zone, the charged grooves then passing on at what is herein described as a slow rate through a large angular distance, preferably greater than 180, to the position where it is transferred under slight pressure to the porous backing, during which period the solvent of that part of the adhesive mass in the grooves located at the exposed surface of such mass and to some extent down into its thickness, evaporates to change the state of this outer part of the thickness of the adhesive mass from the wet state of low cohesiveness to the stiffer readily adhesive and more cohesive condition whilst leavsay one-half of an inch. before nesses greatly exaggerated.

ing the remaining portion of the thickness of the mass r at and towards the base of the grooves still in the wet state of low cohesivesness upon reaching the transfer position, where the porous backing passing around a transfer roller having the same surface speed as the main roller, but opposite direction of rotation, is pressed against the main roller by the transfer roller to cause the exposed adhesive surface of the patterned adhesive and cohesive mass in the outer part of the grooves to gical dressings including medicated strips or: pads, ac-

, derstood that the porous .backing.

from the least cohesive wet-portion at the .base of the grooves without excessive stringing, and it has been found thatconsiderably more than 50% of the patterned mass in the grooves can be transferred in this way.

.The slight stringingfwhich upon occasion may occur.

is not detrimental to theresult as the strings or stretchings of a few stripes of the patterned adhesive mass which may extend at the time of transfer between the main roller and the porous backing, rarely attain-a length ofthey break and have 1 an inappreciable effect on the. pattern of pressure sensitive adhesivespread on the porous backing. I

In order that the invention may be better understood, it will now be described, with, reference to the acco'm-i panying drawings which are given by way of example only and inwhich: F I 1 I Fig. 1 is a diagrammatic sectionalelevation of the rele vant portion of one form of apparatus -for carrying the method according to the present inventon into effect.

Figs.=2, 3, '4, 5, 6 and 7 are greatly enlarged fragmentary portions of Fig. 1 in the positions indicatediby the arrows II,'III, IV, V, VI and VII respectively.

Fig. .8 is a view somewhat similar to Fig. 6 but taken" in another position.

Fig. 9 shows a plan of a portion of a backing with a'.

' patterned spread of an adhesive mass in accordance with the invention located thereon, to a scale larger than that of Fig. 1 but smaller than that of Figs. 2 to 3. Fig. 10 shows a side elevation of Fig. 9 with the thick- Figs. 11 and 12 are similar to be hereafter referred to.

Fig. 13 shows a medical and surgical dressing made in accordance with the invention in the form of a continuous band or band 'viewsto Figs. 9 and '10;

age carrying on one surface the patterned spread of ad-,,

hesive.

Fig 14 shows an end elevation of Fig. 13.

Fig. 15 shows a view similar to Fig. 13 but with the adhesive surface of the dressing carrying in an intermediate position a continuous medicatedstrip or pad of suitable material.

Fig. 16 shows an end view of Fig. 15.

Figs. 17 and 18 show a plan of two examples of surcording to the present invention, and r Fig. 19 is a view similar to Fig. 9 showing another example of the patterned spread, but to -adargerscalef vIn carrying the invention into; efiect it shouldbe uiican; be .of an suiten plan' of a portion of a continuous,

- er Pastime b wate r oth r li uids, there composition for su chan adhesive-ln assz r which in a practical able material as hitherto used for the manufaeture of,

2,94g,ees

adhesivemedieal and surgicaldressings provided it has a minimum moisture vapour permeability of 2,000 grammsevs s q metre W hea a 40 ape-saith Q 1-S t w h nud t T e, upper l ht ers ds .unon- 1h a rt eal r as 2? dr s st q fe manufa tured; or

p twhere t eed o be s stant to' mrpe. ta: sis-no; real: nape: .l i h b whe t e upp ittlfillfindsi lPQ the abilityof the porous backing, to resist'imm'ediate penetration by-water and other liquids, porous :backiss-i h v a mo tur iva pourpermeability of 55000 grammes per square metre per 24 hours have beenifound suitable. t

'IY-he porous backing can be of any material hitherto Used 01 which is found tolbe suitable for usenwith jmedf 18; is a transfer roller which .is' preferably of. a re-.. silient material, for examplehard. rubber, mounted upon a shaft 29 and driven in theidirection of the arrow 30 so that it has the same..peripher .al speed as that of the .34 in such a mannerthat, as hereafter explained, in

this, the transfer:positionfthe backing c'ompressedbeica'l andsurgical dressings Thus, it canib'e afilm or;

thickness of flexible thermoplastic materialwhich'is rendered porous in anysuitable'mannen for example by prickingpunching, or. otherwise perforating. In {some casesit is made porous or microporous during its manufacture. In this last instance it can, for'example, be

'ofc-the 'mic'roporou's polyvinyl chloride film known un der the registered trademark Porvic. In other cases it can be rendered porous by foaming-3- Obviously, it als'o'can be formed from a suitable woven'or other tex tile fabric. I

nysolvent-thinned pressure sensitive rubber based adhesive suitable for'medical and surgical dressings can be -used.*Amongst others, the following is' a suitable.

emit. rubber Dissolved in afpetroleur'n spirit to give about 50%- solids content by" weight.

-The :above composition in the 50% byjweight of petrol'eum spirit. is r-an example of the adhesive *mass' in what have been termed the wet state of low cohesiveness; t H v In the particular method of carryingtheinvention finto eifect shown in Fig 1, 2011s the mainr'oller of steel embodiment has :a diameter of slightly more than 3'1 This is mountedon a shaf t wlich is driven in the direction of the arrow 22. The

" rone; isjof "desired airialflength and from cnd to an has cut on its curved surface In the practical embodi- In the rotation of the main roller the filled grooves 23 'emergiri'gfromjunde'r the doctor blade 27 travel 7 through the distance represented by I the dimension D and which extends some 225- of the circumference of the said roller to attain the transfer position. From this position havin'g had transferredftherefrom the majority 'o'f the adhesive mass contained therein, they travel thro gh the distancerepresented'by'the dimensionR and Qwhieh extends; some 45 9 of the circnmferenee of: the Y roller, to pass under the doctor blade 26 to'the ini 1 term: of the hopper 24 form-filling; i

Parts by weight tween the two rollers, projects slightly into the grooves in the actual position of transfer. In Fig. 1 the patterned spread of adhesive indicated by the numeral issh'own' onthe'backing which has passed the transfer position and is on its way to the drier. The operation takes place at roo grooves 23 travel some fi" from the doctor'blad 2730 t ns rfr si ioa i d we? r ne t e n. 7

proxi atel 8 e onds 7 7 It ld b emrha ed' ca y n h methqii t 7 thereof slightly to recede from what may be term thicker se ctionlines included to g l strettk fih pd ag r V the adhesive mass in right-hand'helical grooves'2 3 located at 4 5 to the axis, twhich eros'sron said surface. i

memos grooves are 0. 022 deep bevelied at the sides,v 7 0.036" wide at the surface, 0.015" wide at the 'base," 1 and spaced apart with a pitch of 0.100". V "I4 is a hopper for the solvent-based adhesive mass 25in the wet state, which is bounded circumferentially 1' of the roller 20 by doctor blades 26 and 27 the lower 7 ends of which include of the circumference of the main roller 20 between them.

fi s t i w e tree L3v fi t'va'ss f time be n the hopper 24 andjfor example, reaches the position shown by the, arrow Han enlargement of which is shown 7 n l h a s s s ed th t j h ve mass itsjwet state Fig, eetion lines all of thesame In sing'from the? PQSIQQII II to the position I-I'Ifthe outer surface of the adhesive'mass, which is a max mum area owin'g' to the bjeveliing of the sides of the grooves is exposed to, the ,a'tniosphere'which evaporates the sol- I vent from this surface and tea slight extent down into the thickness of the adhesive mass, and by the consequent slight shrinkage of, the mass causes the outer 'su face the outer plane of the 'groove.

"This is indicated in Figw 3 where theou "erm ostpart of the adhesive mass'has some l l "represent the change offstate of this outer portion ofthe mass in 'the groove.

IVand as exemplified in 4, 'here the solvent has be'en removed to "a greater depth ofthe thickness: of th'e adhesive I mass in the" gr the interior longer se tio i e j tfisi.

A as shown t e; row

heavier section lines.

with the composition in the wet state, that is, having 50% by weight of solvent, it should be "observed'that the solvent contentof the'hard en ed portion of the adhesivemass down to a depth as indicated by the thickened secthe mass in the grooves. j V f Although in'the particular exampledealt with the" weight of the solvent is 50% "of the weight of the mass} ifl r a bf e" a toma e patella a s t vent willalso vary. some cases this will be greater temperature (approximately 20 6,) and in the-example-under consid ,erationthe speed oftravel imparted to the-backing is;

approximately 20" per minute, and this also is the speed of 'driveof the periphery of' the main grooved roller 20. ,From heabove be appreciated that the filled' Passing onl to. the position representedby 'thearrow we and the shrinkage also is] greaterl The increased cohesiveness of the portion of the groovef'coming on thefexteriorfl of: the said mass and to a still greater; extent? passing to A i f ae s is flia' rb th he er a 517- vndifi n ifi n Fig. 5, the sh in s ti e t and t e1 h,0 n? creased cohesiveness also greater, as indicated bythe ,5 than 50% and in others less than 50%. In cases where a greater proportion of rubber than that given in the particular example, is used, a greater proportion of solvent also will be used to bring the mass in its wet state to the required consistency.

In Fig. 6, although the contacting surfaces of the transfer roller 28, porous backing 31 and main grooved roller 20 are circumferentially curved, they are shown rectilinear as owing to the great enlargement above full size (about twenty times) these contacting portions can be regarded for the short distance concerned as rectilinear. From Fig. 6 it will also be realised that the transfer roller 28 is proceeding in the direction of the arrow 36, the porous backing 31 in the direction of the arrow 37 and the main grooved roller 20 in the direction of the arrow 38, Whilst the transfer roller 28 is pressed against the porous backing 31 in the direction of the arrow 39. Due to this pressure the portion of the porous backing 31 held between the transfer roller 28 and the ungrooved portion of the main grooved roller 29 is compressed and this is indicated by the reference C, Fig; 6. However,

the portion of the porous backing coming between the transfer roller and the grooves is not compressed and when this uncompressed portion of the porous backing actually attains and passes through the transfer position and comes into coincidence with a groove 23, it pro jects into such groove. This is indicated at 40, Fig. 6, and the projection is sufficient to extend into the groove through the space left due to the shrinkage of the adhesive mass so that the surface of the porous backing is pressed on to the suificiently adhesive surface of the adhesive mass for this latter to become adherent thereto.

On the continuing rotation when the running surfaces of the two rollers diverge, as a result of this adhesion the patterned spread of adhesive is readily withdrawn from the grooves of the main roller 20, despite any slight tendency to string there may be in the position of, what may be termed, the plane of separation indicated by the arrows 41, Fig. 6.

In the result, the said patterned spread passes off as shown by 35, Fig. 1, whilst the the transfer position pass onwards towards the hopper 24- through the position shown by the arrow VII, Fig. l, and exemplified in Fig. 7. figure it will be seen that the groove 23 has at the base thereof a small amount of the adhesive mass 42 which is still more or less in the wet state. This passes below the doctor blade 26 into the hopper 24 for the re-charg ing of the grooves. It has been found in practice that these small residues of adhesive mass passing back into the hopper are kept soft by the adhesive masses which re-charge the grooves and even after some 48 hours or more continuous working the grooves still carry out their functions without any of the adhesive mass hardening therein even at the base.

Fig. 9 shows to a scale well above full size a portion of the patterned spread of adhesive 35 on the backing 31, 44 being the adhesive and 45 the porous backing, and it should be emphasized that the pattern in practice has been uniformly consistent and clear cut.

To emphasise the fact that after the filled grooves emerge from beneath the hopper there should be a welldefined time period which can be represented by the arc to he travelled at a certain speed before the patterned spread of adhesive is transferred to the backing in order to enable the state of the adhesive mass carried in the grooves to change as hereinbefore set forth, Fig. 8 represents (in a view similar to Fig. 6) the condition that would exist were the transfer to be attempted in the position, say, represented by the arrow II of Fig. 1. In this case the adhesive mass is as shown in Fig. 2 in the Wet condition and there is no entry of the backing into the groove. In the result, under the pressure in the direction of the arrow 39 there is a mere printing of the Wet adhesive on to the backing which gives no definition grooves proceeding from i From this last-mentioned a ias.

and which leaves so little thickness of adhesive mass that.

it is insufiicient to give adequate adhesion to the skin. A somewhat similar result would be obtained if the transfer position were at the arrow VI but the speed of the main roller 20 greatly increased.

To some extent Figs. 11 and 12 attempt to illustrate. this and from Fig. 11, where 44 is the adhesive and 45 the porous backing, it will be seen that although it is desired the pattern should be as indicated more or less in dotted lines, yet the printed pattern is but a sprawl. Similarly, in Fig. 12, where the thicknesses are greatly exaggerated, it will be appreciated that the thickness of the adhesive is insufficient.

Figs. 13 and 14 show an example of a surgical dress-,

ing in the form of a continuous band having the patterned spread of adhesive applied by the method in accordance with the invention. I

In carrying the method according to the invention into efiect as particularly described in relation to Fig. 1, a roll of porous backing materiakfor example that known under the registered trademark Porvic, some 11" wide, co-operates with a roller of the same axial length to produce a roll of surgical dressing which is cut into strips of the width shown in Figs. 13 and 14.

In some cases, and as shown in Figs. 15 and 16, such a strip carries on its adhesive surface a continuous medicated dressing or pad 43 in'a position intermediate its width.

Further, the porous backing with the patterned spread applied according to the invention can be cut up into so-called fdressings of various sizes such as illustrated in Figs. 17 and 18 which carry in a central position on the adhesive surface medicated pads or strips.

In the example shown in Fig. 19, which is to a much larger scale than fullsizc, the patterned spread shown by 46 in place of being rectilinear strips spaced apart at a desired pitch and crossing at right angles, is replacedby longitudinally extending wavy strips spaced at a desired pitch and transverse rectilinear strips spaced at a desired pitch crossing the wavy strips.

In some cases the patterned spread of adhesive may consist 'of words only or a combination of words with stripes. That is to say, the letters of a word are formed by an arrangement of grooves to receive the wet adhesive and these grooves are interconnected to give continuous runs and to leave ungrooved spaces ina uniform manner. I

Whatever the arrangement of the patterned spread of adhesive, for adequate functioning it is preferred that some of the area of the backing should be covered,

by the adhesive mass and some 50% uncovered. Of course, the invention is not limited tothesepercentages as somewhat more than 60% could be covered and some- What less than 40% uncovered. Further, for strict medboundaries of any adjacent strips should not be less than ical and surgical purposes it is preferred that the width of any strip of adhesive on the backing should not ex-v ceed 0.25 and in this case the distance between the boundaries of any adjacent strips would also be substantially 0.25". Similarly, also for strict medical and surgical purposes, the minimum distance between the 0.025 and in the majority of cases with this narrow uncovered portion of the backing the strips would have substantially the same width.

Highly successful results were obtained by the apparatu particularly described herein operating with the solvent-based adhesive also as herein described, but it should be understood that slight variations in the conditions can be compensated for, for example by adjusting the slow speed of rotation of the main grooved when It should be further emphasised that by working at such a slow speed and at room temperature, with the particular roller having grooves 0.022" deep it is comparatively easy to determine the depth to which the adhesive mass fed into the grooves is affected by these two fac- 3. In the manufacture'of a Flirther, it will be understood, given the fact that the depth'of the groove must of necessity be but slight and comefbetween the normal limits of 0.0,lf"and.

01160", the speed of travel to give the correct result for any particular adhesive mass 'in theWet state to pass through a certain distance from the charging to the trans- 1 fer position, can be ascertained experimentally and subsequently utilised inithe operation of the process.

Apart from the above, it should be pointed out that although in all cases the'speed of the roller will bev s low,fyet it is determined by the actual diameter of the roller. In the example particularly described this is slightly more than 3" but if, for example, it were twice that diameter then the speed, although still slow, would be increased. 7 Thus, it'must be specifically understood herein that thefterrn slow'spee'd has wide limits, the "highest slow speed of course being that determined by the ,rnaximum' practical diameter of the jm'ain roller and the lowest slow speed being that determined by the minimum practical diameter of the main rollers,

The invention is not limitedto the precise details here-v j' in set forth, as these may be varied to suit particular or requirements. 7 t i 'What I claim is: g

i. In the manufacture of adhesive medical and surgical dressings of the type set forth, the method of applying a solvent-thinned pressure sensitive rubber based adhesive to the porous backing wliich'utilises as a carrier for the patterned mass a slowly turning main roller the cylindrical curved surface of which has cut thereon shal low grooves in accordance with the pattern, to which grooves, while the roller is turning, the adhesive mass, at room temperature and in 'awet state of, low cohesiveness .is fed at one zone, the charged grooves then pass-- ing throughthe major, portion of rotary movement of said roller to a transfer position spaced a sufiicient angular distance away from said adhesive feeding'zone, :to

allow, by evaporation of some of the solvent therein,

the greater part of the thickness of the adhesive mass in the grooves to change from the Wet state to a readily adhesive stifier and more cohesive condition but still to. e

when in the wet state for. feeding to the; grooved main roller, and in which; the speed of rotation and angular spacing between-the feeding and transfer positions is such that the solvent content of the stiffened portion of the adhesive mass of high cohesiveness at the transfer position is reduced to substantially 30%. f' v 4. A method of making surgical and medical adhesive dressings having a porous backing coated on one side with a patterned spread of solvent thinned pressure sensitive rubber based adhesive sufiicient to give adequate adhesion to the skin, but leaving a multiplicity of uncoated areas for the escape of perspiration consisting in a feeding solvent thinned pressure sensitive rubber based adhesive at room temperature to a slowly rotating roller so that the adhesive will be deposited in peripheral grooves therein by gravity, conveying said adhesive on said roller throughout the major portion of its rotary movement, continuously feeding said strip of porous material into transfer relationship with said adhesivein a zone adjacentthe feeding point" and are; said adhesive has been conveyed and exposed to the! atmosphere throughout the major portion 'of its travel before being transferred to said strip and thus permit the greater part of the thickness of the adhesive mass in the grooves to change from the wet state to a readily adhesive stiffer and more cohesive condition but still leave a residue of said mass in the wet state at the base of the grooves, said continuously fed strip being moved into engagement with the roller at substantially the same peripheral speed where by'sa'id adhesive material will have its congealed portion presented to said hacking in transfer relationship therewith.

I to, the porous backing by a slowly rotating'main roller leavea residue of saidmass in the Wet state at the base of the grooves to readilylpermit displacement of said stiffer. 5 portion of said adhesive from said grooves, the transfer of the patterned adhesive mass to the porous backing being effected by a transfer roller'havin'g thesame peripheral 'speed astbut rotating in the opposite direction to the rnain grooved roller,'the backing moving with and V passing around the said transferi-roller and being pressed thereby againstthe grooved surface of the main roller to contact with the exposed adhesive surface of the patterned'hdlesive andcohesive mass in the outer part of the grooves, to cause such mass to adhere't'o the surface i of the backing and eifect by the continued turning i'riove ment of the rollers the transfer of the patteruedadhe-f sive mass 'from the 'grooves to the backing by the easy separation of the stiffened portion of the adhesive mass 7 of high cohesiveness in said grooves from the still-wet residue of the adhesive mass at the base of the grooves.

2 In the manufacture of adliesive'medical and surgical dressings, the method :of applying the solvent-thinned pressure sensitive rubber based adhesive to the porous backing as claimed in claim' 1, in which the rate ,of rotation of the grooved roller and the distance; of travel for th'e adhesive from the position where it emerges "from the feeding zone to the transfer position is such that the. solvent content of the seams portion of thea'dhesive mass" to be transferred at the transfer position is substan tially hal fthe solvent'content 'of the wet adhesive mass as'it leavesthe feeding zonei A dhesive ,medieal n surgi; dressin s t me b ap l n the s ven -th n pressure sensitive ruhberlbasedi adhesive "to the porous s s a s e md in, a m 1; n whi th a s b nqeq adhesive includes substantially 50% by weight of solvent 7 having a peripheral speed of approximately 20 inches per minute, and a peripheral surface provided with grooves "which are arranged 'in 1 accordance with a pattern and which, during the rotation of the roller are fed at one zone with the adhesive highly diluted by a-solvent and at room temperature whereupon the filled grooves, due to the slow'rotation of the roller travelthrough the major portion of rotary movement of said roller to a transfer position which is arranged at such a distance from the adhesive feeding zone that, during this period of travel,

a large proportion of the solvent present in the outer layers of the adhesive that fills the grooves will evaporate,

these layers assuming a stifier adhesive consistency while the adhesive at the base of the groovesstill remains in a V thinned state to readily permit displacement of said stifier" portion of said adhesive from said grooves, so that on the transference of the adhesive to the porous gbacking by being pressed 'on torthe grooved roller by means of a transfer roller and carried around with it, the outcr:stiffened layers of the adhesive adhere thereto firmly and by-the'continued movement of the rollers are readily separated at this position from the thinned adhesive still remaining insthe base of the grooves.

References Cited in the file of this patent V UNITED STATES PATENTS May'3, 19 38 o 7 on on REFERENCES VCraWfOrdQEarl A.: Gravureflune 1955 In the manufacture of adhesive medical and surgicaldressings of the type set forth, the method of applying a solvent-thinned pressure-sensitive rubber-based adhesive 

1. IN THE MANUFACTURE OF ADHESIVE MEDICAL AND SURGICAL DRESSINGS OF THE TYPE SET FORTH, THE METHOD OF APPLYING A SOLVENT-THINNED PRESSURE SENSITIVE RUBBER BASED ADHESIVE TO THE POROUS BACKING WHICH UTILISES AS A CARRIER FOR THE PATTERNED MASS A SLOWLY TURNING MAIN ROLLER THE CYLINDRICAL CURVED SURFACE OF WHICH HAS CUT THEREON SHALLOW GROOVES IN ACCORDANCE WITH THE PATTERN, TO WHICH GROOVES, WHILE THE ROLLER IS TURNING, THE ADHESIVE MASS, AT ROOM TEMPERATURE AND IN A WET STATE OF LOW COHESIVENESS IS FED AT ONE ZONE, THE CHARGED GROOVES THEN PASSING THROUGH THE MAJOR PORTION OF ROTARY MOVEMENT OF SAID ROLLER TO A TRANSFER POSITION SPACED A SUFFICIENT ANGULAR DISTANCE AWAY FROM SAID ADHESIVE FEEDING ZONE, TO ALLOW, BY EVAPORATION OF SOME OF THE SOLVENT THEREIN, THE GREATER PART OF THE THICKNESS OF THE ADHESIVE MASS IN THE GROOVES TO CHANGE FROM THE WET STATE TO A READILY ADHESIVE STIFFER AND MORE COHESIVE CONDITION BUT STILL TO LEAVE A RESIDUE OF SAID MASS IN THE WET STATE AT THE BASE OF THE GROOVES TO READILY PERMIT DISPLACEMENT OF SAID STIFFER PORTION OF SAID ADHESIVE FROM SAID GROOVES, THE TRANSFER OF THE PATTERNED ADHESIVE MASS TO THE POROUS BACKING BEING EFFECTED BY A TRANSFER ROLLER HAVING THE SAME PERIPHERAL SPEED AS BUT ROTATING IN THE OPPOSITE DIRECTION TO THE MAIN GROOVED ROLLER, THE BACKING MOVING WITH AND PASSING AROUND THE SAID TRANSFER ROLLER AND BEING PRESSED THEREBY AGAINST THE GROOVED SURFACE OF THE MAIN ROLLER TO CONTACT WITH THE EXPOSED ADHESIVE SURFACE OF THE PATTERNED ADHESIVE AND COHESIVE MASS IN THE OUTER PART OF THE GROOVES, TO CAUSE SUCH MASS TO ADHERE TO THE SURFACE OF THE BACKING AND EFFECT BY THE CONTINUED TURNING MOVEMENT OF THE ROLLERS THE TRANSFER OF THE PATTERNED ADHESIVE MASS FROM THE GROOVES TO THE BACKING BY THE EASY SEPARATION OF THE STIFFENED PORTION OF THE ADHESIVE MASS OF HIGH COHESIVENESS IN SAID GROOVES FROM THE STILL-WET RESIDUE OF THE ADHESIVE MASS AT THE BASE OF THE GROOVES. 